Fuse plug



Jan. 13. 1925.

l,523,125 o. H.v JUNG FUS E PLUG Fil ed May 8, 1922 Patented Jan. 13, 1925.

UNITED sTA'r-Es iszaiz PATENT OFFICE.

osoAn JUNG, or MIWAUKEE; Wisconsin.

FUSE PUG.

Application filed May 8, 1922.

' ino' metal ferrule and suitable end portions.

rI`he invention refers to socket fuse plugs. Heretcfore it has been coinmon practice to provide fuses of this general type With some 'transipiarent surface, Whereby the vfuse can be usually inspected to determine whether 01' not it has been blown. In such instances, the visual signal has been found to be impractical, for the reason that the transparent surface provided for inspection frequently becomes blurred and it is, therefore, difhcult to determine whether 'or not the fuse is burnt or bloivn. The invention, therefore, provides a simple, economical and effective means.r whereby the fuse can be physically tested as to its condition.

In the inanufaoture of porcelain plugs,the porcelains are apt to be cracked in handling` pai'tieularly When caps are clinched thereon. This creates a danger of short circuit. By making his shell of fibre, applicant avoids this danger.

Most plug's depend upon venting` About the onter edge of caps gases are expected to escape around the clinched edge. This generally unreliable, as uniform operation depends upon uniform clinching, a practical impossibility due to variations of porcelain. in applicanfls device, the provision of five uniform vent holes in the cap makes a re' liable and uniform venting system. By the use of powder and the restricted venting system, applicant avoids bad flashes, violence. and a smoked exterior.

In mica capped plugs there is a possihility of installing mica discs too thin to Withstand severe blow outs. The steel caps of uniform thickness in applicanis invention eliminate this danger.

In many porcelain plug fuses the Variation of porcelain causes caps to fit loosely, permitting vicious venting. Also, caps have a tendency to shift to one side, preventing Serial No. 559,271.

uniforin clinching. In applicant7s novel structure, this defect is prevented.

Most porcelain plug; fuses are provided With chambers or recesses to receive the end of the fusible link, which is to be soldered to the -screw shell. These chambers or recesses are sealed With various compounds. This is an unreliable operation for it is inde'ed ditficult to make a practically dependable seal. Defective sealing Will einit dangerous flashes, generally destroying both plug and cut-out disc, it becoming a dan- ,'erous fire hazard and an object of the invention is the obviating of this unreliable operation.

In some porcelain plug fuses an effort is made to pour solder between the screiv shell and the porcelain body in order to make contact between the link and screiv Shell. In many instances this has proven unreliable, i'esulting in the destruction of both fuse and cut-out. VIn the novel construction, the links are soldered in plain view. Defeets, if any, are readily dis'covered by the *ispector and remedied before the product leaves the factory. A very important feature of the fusible link is the provision of a restricted portion which localizes the blow-out point, thus making for Superior operation on rating and short circuit performances. as compared With Wire or fiat strips Without restricted portions.

Tith the above and other objects in view. which will appear as the description proceeds, my invention resides in the novel construction` combination and arrangeinent of parts, substantially as hereinafter described and more particularly defined by the appended claim, it being understood that such changes in the precise einbodiment of the herein disclosed invention ma)v bel made :is come Within the scope of the claiin.

In the accompanying` drziwing. have illustrated one complete example of the physical embodiment of the present invention constructed according` to the best mode I have so far devised for the practice-.l application of the principles thei'eof, and in which:

Figure 1 is a sectional elevation of the fuseplug einbodying the. features of the invention, the section being' indicated by line 1 1 of Figure 2.

Fig'ure 2 is a cross section on the line. of Figure 1.

lltl

Figure 3 is a rear end view of the plug.

Fib're shell 10 has secured to one 'end a metallic ferrule 11 provided with screw threads 12 adapted to be received in the standard socket. Fitted to the rear end is a centrally apertured fibre disc'13 which is secured to shell 10 by inturned fiange 14: of ferrule 11. Any suitable non-conducting material can be used in the disc. Ferrule 11 may be secured to shell 10 by cement.

The front end of the shell is closed by metallic cap 15 formed with an outwardly directed flange .16. The flange is thereafter extended so as to form a bead 17 spun over the outer surface and Vfirmly securing the cap.

Fitted through the aperture in disc 13 is a terminal 18. Bifurcations 19, 19' clinch the terminal against disc 13 and the fusiblelink or runner 20 is soldered to bifurcat-ion- 19. Link 20 has a portion 21 intermediate its ends of reduced cross sectional area and one of its ends extends' through shell 10, is

bent forwardly, and clamped between ferrule 11 and the shell, solder 21' securing it in position. Itis apparent that the solder 21' may be applied in a most convenient manner and failure of the solder to secure link 20 to ferrule 11 is practically impossible. Also, the construction of parts is such as to make the mode of soldering` link 20 to bifurcation 19 most convenient.

The shell is adapted to receive a suitablex powder, not shown. Cap 15 is provided with apertures 22 over which a paper label 23 is positioned adapted to be suitably marked to indicat-e proper aniperage and voltage of the fuse.

rThe location of the reduced portion 21 of link 20 is most advantageous, as the fusing action will occur along this reduced extent and it is impossible that the action should occur at the end of the link at which point burning might occur. parts adjacent the solder 21' is such as to eliminate bad flashcs. The provision of vent holes 22 permitting the egress of heated The fitting` of i Attention is directed to the fact that in I practice the label, or memb-rane, 23, is quite thin and is glued or otherwise attached to the cap 15, whereby the apertures therein are sealed. Hence, when a blow-out occurs, the gases will readily puncture the Sensitive membrane, whereby it serves as a visible indicator that the fuse is dead. It should, also, be understood that the thin metallic link 20, at its base, is of greater cross sectional area than the remainder t-hereof, which rcmainder, or weakened strand, extends approximately centrally of the shell and is thereafter folded in a loop and connected to the ferrule 11. Owing to the position of this fusible strand, when fusion takes place, the explosion will radiate from 'approXimate-ly the center of the shell 10, whereby the pressure, due to the gases, is

exerted uniformly in a radial direction.

I claimz- In a socket fuse plug having a fibre Shell,

of and crimped down upon the outer surface of the shell, whereby the same is compressed between the inner and outer fiange walls to eifectually seal and prevent blow out of the cap under gas pressure.

, In testimony that I claim the foregoing Ihave hereunto set my hand at Milwaukee, in the county of Milwaukee and State of o lVisconsin.

i oscAR' ii. JUNG. 

